System and method for dynamic channel allocation

ABSTRACT

An exemplary system and method for dynamic channel allocation in an LMR system includes using one or more preference indicators to dynamically determine a channel allocation priority to be used for channel allocation when channel allocation requests are received. The preference indicators may include a channel failure indicator (e.g. a channel health indicator based on repeater failures), a channel priority indicator, a radio frequency interference indicator, a high reflected power indicator, an excessive current drain indicator, a loss of backbone communications indicator, and a channel usage indicator. If more than one preference indicator is used, the channel priority ranking may be determined using any of a variety of weightings and prioritizations of the various preference indicators to dynamically generate the channel allocation priority. The dynamic channel allocation system may include one or more site controllers, servers, and/or one or more processors configured to implement the method of dynamic channel allocation.

RELATED APPLICATION

Pursuant to 35 U.S.C. § 120, this application is a continuation of U.S.patent application Ser. No. 15/641,747, entitled “System and Method forDynamic Channel Allocation,” filed Jul. 5, 2017, and naming Ronald LeeBane and Brian J. Austin as inventors, which is a continuation of U.S.patent application Ser. No. 14/935,270, entitled “System and Method forDynamic Channel Allocation,” filed Nov. 6, 2015, and naming Ronald LeeBane and Brian J. Austin as inventors, which claims the benefit andpriority from U.S. Provisional Patent Application Ser. No. 62/076,473,entitled “System and Method for Dynamic Channel Allocation,” filed Nov.6, 2014, and naming Ronald Lee Bane and Brian J. Austin as inventors,both of which are incorporated by reference herein for all purposes.

TECHNICAL FIELD

This disclosure relates in general to a system and method for dynamicchannel allocation in a communications system and, in particular, to animproved system and method for dynamic channel allocation in a landmobile radio system, including a simulcast and a non-simulcast landmobile radio system, using one or more preference indicators.

BACKGROUND OF THE DISCLOSURE

Land mobile radio (LMR) systems are used by municipalities, governmentalentities, including police, fire, medical, and military firstresponders, and other organizations to provide a private, wirelesscommunications network using mobile and/or stationary radio units tocommunicate with one another over a specific geographic area. An LMRsystem can be as simple as two subscriber units communicating betweenthemselves and a site over preset channels, or they can be complexconsisting of hundreds of subscriber units and multiple sites.Generally, an LMR system includes a plurality of sites positioned indifferent locations in the specific geographic area to provide thedesired coverage and bandwidth. Each site may include an antenna, a sitecontroller, and a plurality of repeaters that include a transmitter andreceiver at designated or desired frequencies. In certain embodiments,the sites, such as the site controllers, may communicate with each otherthrough a backbone data network, such as an IP data network or theInternet, to assist with communications needs between the sites, such ascall-setup activities and administrative functions needed for operatingan LMR system.

An LMR System may, generally, be categorized as simulcast system or anon-simulcast system. In a simulcast trunking LMR system, a channel iscomprised of two or more repeaters, each having common transmitfrequencies, and common receive frequencies, but located at differentgeographical locations. The site locations are chosen to provide a widercoverage area than is possible with a single location. In such simulcastsystems, repeater failures can result in a reduction in capacity, areduction in coverage, or both. Consider, for example in a nine channel,three site simulcast LMR system, the failure of a single repeater at onesite. If the channel is allowed to be included for use in subsequentcommunication requests, the RF coverage will suffer, due to the loss oftransmit and/or receive functionality in the geographical area normallycovered by the failed repeater. If the channel is not allowed to beincluded for use in subsequent communication requests, the system willoperate over the preferred coverage area, but with reduced capacity. Inthis failure scenario, it is likely that the reduced capacity result ispreferred over the reduced coverage area result.

Consider an alternate failure scenario where a site loses power, causingall repeaters at that site to fail. If the same preferred action fromthe previous scenario were applied in this case, all channels would beexcluded from subsequent communication requests, resulting in zerocapacity for the system. For this failure scenario, the reduced coverageresult would be preferred over the zero capacity result.

When a call is setup in an LMR system, channels, which are comprised ofunderlying repeaters at one or more sites, are to be effectivelyallocated or various problems and disadvantages may occur, such as thosejust described, including decreased call coverage area, decreasedbandwidth or capacity, and call quality.

SUMMARY

In a first aspect, there is provided a method for dynamic channelallocation in a land mobile radio communications system that includesallocating a control channel and a traffic channel based upon at leastone preference indicator. The method may include determining one or morepreference indicators for various channels for use in allocating theplurality of channels, wherein each of the plurality of channels isassociated with one or more repeaters of a plurality of repeaterslocated at a plurality of sites of the land mobile radio communicationssystem, determining a priority ranking for use in allocating each of theplurality of channels based at least in part on the one or morepreference indicators, and receiving a first channel allocation requestto allocate one of the plurality of channels as a control channel. Themethod may further includes allocating a first one of the plurality ofchannels as the control channel in response to the first channelallocation request by selecting the first one of the plurality ofchannels based on the highest ranked channel of the priority ranking foruse in allocating each of the plurality of channels, receiving a secondchannel allocation request to allocate one of the plurality of channelsas a traffic channel while the first one of the plurality of channels isallocated as the control channel, and allocating a second one of theplurality of channels as the traffic channel in response to the secondchannel allocation request by selecting the second one of the pluralityof channels based on the then highest ranked channel of the priorityranking for use in allocating each of the plurality of channels.

In one embodiment of the method, the method further includes updatingthe priority ranking for use in allocating each of the plurality ofchannels based at least in part on changes to the one or more preferenceindicators.

In another embodiment of the method, the method further includesperiodically updating the priority ranking for use in allocating each ofthe plurality of channels.

In still another embodiment of the method, the method further includesupdating the priority ranking for use in allocating each of theplurality of channels based at least in part on changes in at least twoor more of the one or more preference indicators.

In still yet another embodiment of the method, at least one of the oneor more preference indicators includes a channel failure indicator foreach of the plurality of channels that corresponds to the currentoperational indicator of the plurality of repeaters associated with eachchannel.

In one embodiment of the method, the channel failure indicator isdetermined for each of the plurality of channels and is based on thepercentage of operational repeaters associated with a particular channelas compared to the total number of repeaters associated with thatparticular channel.

In yet another embodiment of the method, the one or more preferenceindicators includes at least one from the group that includes a channelfailure indicator, a channel priority indicator, and a radio frequencyinterference indicator.

In still yet another embodiment of the method of dynamic channelallocation, the one or more preference indicators includes a channelfailure indicator for each of the plurality of channels that correspondsto the current operational state of the plurality of repeatersassociated with each channel, and a channel priority indicator thatincludes a static ranking of each of the plurality of channels.

In another embodiment of the method, the one or more preferenceindicators includes a channel priority indicator that includes a staticranking of each of the plurality of channels.

In yet another embodiment, the one or more preference indicatorsincludes a radio frequency interference indicator that corresponds toradio frequency interference levels for each of the plurality ofchannels.

In one embodiment of the method, the one or more preference indicatorsincludes a high reflected power indicator that corresponds to reflectedpower levels related to each of the plurality of channels.

In still another embodiment of the method, the one or more preferenceindicators includes at least one from the group that includes a channelfailure indicator, a channel priority indicator, a radio frequencyinterference indicator, a high reflected power indicator, an excessivecurrent drain indicator, a loss of backbone communications indicator,and a channel usage indicator.

In yet another embodiment of the method, the land mobile radiocommunications system is a simulcast land mobile radio communicationssystem.

In yet still another embodiment, the land mobile radio communicationssystem is a P25 trunking system.

In one embodiment of the method, the land mobile radio communicationssystem includes a plurality of sites positioned at separate locationsand in data communication with one another using a data communicationsnetwork. And in another embodiment of the method, the datacommunications network is a backbone data communications network.

In another embodiment of the method, determining the priority rankingfor use in allocating each of the plurality of channels is based on aweighted average of at least a first preference indicator and a secondpreference indicator of the one or more preference indicators.

In still another embodiment of the method, determining the priorityranking for use in allocating each of the plurality of channels is basedon a weighted average of at least a first preference indicator and twoor more of the indicators from the group including or consisting of achannel priority indicator, a radio frequency interference indicator, ahigh reflected power indicator, an excessive current drain indicator, aloss of backbone communications indicator, and a channel usageindicator.

In a second aspect, there is provided a method for dynamic channelallocation in a land mobile radio communications system that includesdetermining a first and second preference indicator and allocating afirst channel and a second channel based upon at least the firstpreference indicator. The method may include determining the firstpreference indicator and the second preference indicator for each of aplurality of channels for use in allocating the plurality of channelsassociated with one or more repeaters located at a plurality of sites.The first preference indicator includes a channel failure indicator foreach of the plurality of channels that corresponds to the currentoperational state of the plurality of repeaters associated with eachsuch channel, and the second preference indicator is one or more fromthe group including or consisting of a channel priority indicator, aradio frequency interference indicator, and a high reflected powerindicator. The method may further include determining a priority rankingfor use in allocating each of the plurality of channels based at leastin part on the first preference indicator that includes the channelfailure indicator for each of the plurality of channels, receiving achannel allocation request, and allocating a channel in response to thechannel allocation request by selecting an available channel based onthe priority ranking for allocating each of the plurality of channels.

In one embodiment of the method, determining the priority ranking foruse in allocating each of the plurality of channels is based at least inpart on both the first preference indicator and the second preferenceindicator. In another embodiment of the method, the second preferenceindicator for use in allocating the plurality of channels is the channelpriority indicator that includes a static ranking of each of theplurality of channels.

In yet another embodiment of the method, the second preference indicatorfor use in allocating the plurality of channels is the radio frequencyinterference indicator that corresponds to radio frequency interferencelevels for each of the plurality of channels.

In still yet another embodiment of the method, the second preferenceindicator for use in allocating the plurality of channels is the highreflected power indicator that corresponds to reflected power levelsrelated to each of the plurality of channels.

In one embodiment of the method, the second preference indicator for usein allocating the plurality of channels is one from the group includingor consisting of the channel priority indicator, the radio frequencyinterference indicator, a high reflected power indicator, an excessivecurrent drain indicator, a loss of backbone communications indicator,and a channel usage indicator.

In another embodiment of the method, the land mobile radiocommunications system is a simulcast land mobile radio communicationssystem.

In yet another embodiment of this method, the method further includesperiodically determining the priority ranking for use in allocating eachof the plurality of channels based at least in part on the firstpreference indicator that includes the channel failure indicator foreach of the plurality of channels.

In still another embodiment of the method, the method further includesupdating the priority ranking for use in allocating each of theplurality of channels based at least in part on changes in the firstpreference indicator.

In yet another embodiment of the method, the method further includesupdating the priority ranking for use in allocating each of theplurality of channels based at least in part on changes in the firstpreference indicator or the second preference indicator.

In one embodiment of the method, the allocated channel is a trafficchannel configured to exchange voice communications.

In another embodiment of the method, the allocated channel is a controlchannel.

In still another embodiment of the method, the channel failure indicatoris determined for each of the plurality of channels and is based on thepercentage of operational repeaters associated with a particular channelas compared to the total number of repeaters associated with thatparticular channel.

In yet another embodiment of the method, each of the plurality ofchannels includes one or more repeaters located at a plurality of landmobile radio sites.

In one embodiment of the method, the priority ranking for use inallocating each of the plurality of channels is based on a weightedaverage that includes at least the first preference indicator and thesecond preference indicator.

In another embodiment of the method, determining the priority rankingfor use in allocating each of the plurality of channels is based on aweighted average of the first preference indicator and two or more ofthe indicators from the second preference indicator from the groupincluding or consisting of the channel priority indicator, the radiofrequency interference indicator, a high reflected power indicator, anexcessive current drain indicator, a loss of backbone communicationsindicator, and a channel usage indicator.

In a third aspect, there is provided a land mobile radio communicationssystem with dynamic channel allocation to provide mobile communicationsbetween at least two of a plurality of radio subscriber units. The landmobile radio communications system includes a plurality of sitespositioned at separate locations in data communication with one anotherusing a data network, and wherein each of the plurality of sitesincludes a plurality of repeaters configured to provide a plurality ofchannels for communications between at least two of the plurality ofradio subscriber units, and one or more processors configured to providedynamic channel allocation. The one or more processors may be configuredto provide dynamic channel allocation that includes the capability todetermine one or more preference indicators for each of the plurality ofchannels for use in allocating the plurality of channels, wherein eachof the plurality of channels is associated with one or more repeaters ofthe plurality of repeaters located at the plurality of sites of the landmobile radio communications system, and to determine a priority rankingfor use in allocating each of the plurality of channels based at leastin part on the one or more preference indicators. The one or moreprocessors may be further configured to provide the capability toreceive a first channel allocation request to allocate one of theplurality of channels as a control channel, to allocate a first one ofthe plurality of channels as the control channel in response to thefirst channel allocation request by selecting the first one of theplurality of channels based on the highest ranked channel of thepriority ranking for use in allocating each of the plurality ofchannels, to receive a second channel allocation request to allocate oneof the plurality of channels as a traffic channel while the first one ofthe plurality of channels is allocated as the control channel, and toallocate a second one of the plurality of channels as the trafficchannel in response to the second channel allocation request byselecting the second one of the plurality of channels based on the thenhighest ranked channel of the priority ranking for use in allocatingeach of the plurality of channels.

In one embodiment of the LMR system, the one or more processors arefurther configured to update the priority ranking for use in allocatingeach of the plurality of channels based at least in part on changes tothe one or more preference indicators.

In another embodiment of the LMR system, the one or more processors arefurther configured to periodically update the priority ranking for usein allocating each of the plurality of channels.

In yet another embodiment of the LMR system, the one or more processorsare further configured to update the priority ranking for use inallocating each of the plurality of channels based at least in part onchanges in at least two or more of the one or more preferenceindicators.

In still another embodiment of the LMR system, the at least one of theone or more preference indicators includes a channel failure indicatorfor each of the plurality of channels that corresponds to the currentoperational state of the plurality of repeaters associated with eachchannel.

In another embodiment of the LMR system, the channel failure indicatoris determined for each of the plurality of channels and is based on thepercentage of operational repeaters associated with a particular channelas compared to the total number of repeaters associated with thatparticular channel.

In one embodiment of the LMR system, the one or more preferenceindicators includes at least one from the group that includes a channelfailure indicator, a channel priority indicator, a radio frequencyinterference indicator, and a high reflected power indicator.

In yet another embodiment of the LMR system, the one or more preferenceindicators includes a channel failure indicator for each of theplurality of channels that corresponds to the current operational stateof the plurality of repeaters associated with each channel, and achannel priority indicator that includes a static ranking of each of theplurality of channels.

In still another embodiment of the LMR system, the one or morepreference indicators includes a channel priority indicator thatincludes a static ranking of each of the plurality of channels.

In another embodiment of the LMR system, the one or more preferenceindicators includes at least one from the group that includes a channelfailure indicator, a channel priority indicator, a radio frequencyinterference indicator, a high reflected power indicator, an excessivecurrent drain indicator, a loss of backbone communications indicator,and a channel usage indicator.

In yet another embodiment of the LMR system, the land mobile radiocommunications system is a simulcast land mobile radio communicationssystem.

In still another embodiment of the LMR system, the is a conventionalsystem.

In one embodiment of the LMR system, the determination of the priorityranking for use in allocating each of the plurality of channels is basedon a weighted average of at least a first preference indicator and asecond preference indicator of the one or more preference indicators.

In a fourth aspect, there is provided a dynamic channel allocationsystem configured for use in a land mobile radio communications systemthat provides mobile communications between at least two of a pluralityof radio subscriber units is provided. The land mobile radiocommunications system includes a plurality of sites in communicationwith one another and positioned at separate locations, and wherein eachof the plurality of sites includes a plurality of repeaters configuredto provide a plurality of channels for communication between the atleast two of the plurality of radio subscriber units. The dynamicchannel allocation system may include one or more processors configuredto determine one or more preference indicators for each of the pluralityof channels for use in allocating the plurality of channels, whereineach of the plurality of channels is associated with one or morerepeaters of the plurality of repeaters located at a plurality of sitesof the land mobile radio communications system, and to determine apriority ranking for use in allocating each of the plurality of channelsbased at least in part on the one or more preference indicators. The oneor more processors may be further configured to receive a first channelallocation request to allocate one of the plurality of channels as acontrol channel, to allocate a first one of the plurality of channels asthe control channel in response to the first channel allocation requestby selecting the first one of the plurality of channels based on thehighest ranked channel of the priority ranking for use in allocatingeach of the plurality of channels, to receive a second channelallocation request to allocate one of the plurality of channels as atraffic channel while the first one of the plurality of channels isallocated as the control channel, and to allocate a second one of theplurality of channels as the traffic channel in response to the secondchannel allocation request by selecting the second one of the pluralityof channels based on the then highest ranked channel of the priorityranking for use in allocating each of the plurality of channels.

In one embodiment of the dynamic channel allocation system, the landmobile radio communications system is a P25 trunking system.

In another embodiment of the dynamic channel allocation system, the oneor more processors are further configured to update the priority rankingfor use in allocating each of the plurality of channels based at leastin part on changes in at least two or more of the one or more preferenceindicators.

In yet another embodiment of the dynamic channel allocation system, theat least one of the one or more preference indicators includes a channelfailure indicator for each of the plurality of channels that correspondsto the current operational state of the plurality of repeatersassociated with each channel.

In still another embodiment of the dynamic channel allocation system,the one or more preference indicators includes at least one from thegroup that includes a channel failure indicator, a channel priorityindicator, a radio frequency interference indicator, and a highreflected power indicator.

In one embodiment of the dynamic channel allocation system, the one ormore preference indicators includes at least one from the group thatincludes a channel failure indicator, a channel priority indicator, aradio frequency interference indicator, a high reflected powerindicator, an excessive current drain indicator, a loss of backbonecommunications indicator, and a channel usage indicator.

In still another embodiment of the dynamic channel allocation system,the determination of the priority ranking for use in allocating each ofthe plurality of channels is based on a weighted average of at least afirst preference indicator and a second preference indicator of the oneor more preference indicators.

Other aspects, features, and advantages will become apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings, which are a part of this disclosure and whichillustrate, by way of example, principles of the inventions disclosed.

DESCRIPTION OF THE FIGURES

The accompanying drawings facilitate an understanding of the variousembodiments, and are not necessarily drawn to scale.

FIG. 1 is an overview diagram that illustrates an exemplary LMR systemwith dynamic channel allocation that includes three sites that eachinclude nine repeaters and that each have a designated geographiccoverage area, according to an embodiment;

FIG. 2 is an overview diagram that illustrates an exemplary site of anLMR system in communication with a mobile radio unit, and including anantenna, a plurality of repeaters, and a site controller with one ormore processors, a memory or storage device, and a dynamic channelallocation system, according to one embodiment;

FIG. 3 is a flowchart that illustrates an exemplary method for dynamicchannel allocation in a land mobile radio communications system thatinvolves using at least one preference indicator, such as a channelfailure indicator, to allocate a control channel and a traffic channel,according to an exemplary embodiment; and

FIG. 4 is a flowchart that illustrates another exemplary method fordynamic channel allocation in a land mobile radio communications systemthat includes at least a first preference indicator and a secondpreference indicator, according to another exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 is an overview diagram of an exemplary land mobile radio (LMR)system 100 with dynamic channel allocation. The LMR system 100 includesa first site 102, a second site 104, and a third site 106. The circlesaround each of the sites indicate an approximate geographic coveragearea for such sites of the LMR system 100. Each of the three exemplarysites of FIG. 1 include nine repeaters. For example, the first site 102includes a plurality of repeaters 110, as illustrated, having ninerepeaters. Each such repeater of the plurality of repeaters 110 includesthe capability to transmit and receive. Similarly, the second site 104includes a plurality of repeaters 120, which also includes ninerepeaters similar to the plurality of repeaters 110 of the first site102. The third site 106 also includes a plurality of repeaters 130 thatincludes nine repeaters.

Not shown in FIG. 1 is a data network, such as a backbone network, whichmay be implemented as an IP network, that is used to provide datacommunication between and among the sites of the LMR system 100.Further, various processors, servers, and supporting hardware may beprovided at one or more of the sites, and these are not expressly shownin FIG. 1. This may include, depending on the implementation of the LMRsystem 100, site controllers provided at each site, or at designatedsites. It should be understood that the LMR system 100 may be providedas a P25 system, a trunk system, a conventional system, a simulcastsystem, a non-simulcast system, or virtually any other implementation ofan LMR system.

In operation, a radio subscriber unit, which may be a portable or mobileradio and/or a stationary radio unit, is in communication with one ormore of the sites of the LMR system 100, and a request is made to set upa channel for communication with one or more other radio units. In sucha case, a dynamic channel allocation system includes one or morepreference indicators that may be used to prioritize the availablechannels so that the appropriate or desired traffic channel is selectedwhen the traffic channel request is received. A control channel may beallocated using the same or similar dynamic channel allocation systemand the one or more preference indicators so that an appropriate ordesired control channel is set up at startup and at other designatedtimes when a control channel is needed.

In a simulcast system, a channel, such as a control channel or a trafficchannel, may include a repeater at each of the three sites 102, 104, and106 that transmits and receives on the same frequency. For example, achannel request to set up a control channel may result in a dynamicchannel allocation of a channel that is defined as including a repeater“1” from the plurality of repeaters 110, 120, and 130, from the varioussites of the LMR system 100. One or more preference indicators may beused to rank the nine channels of the LMR system 100. In oneimplementation, a health indicator, which also may be referred to as achannel failure indicator, may be used as the first and only preferenceindicator. The channel failure indicator may be calculated in a varietyof ways. For example, if one of the three repeaters for channel one isnot available, a simple percentage of 67% may represent the channelfailure indicator of channel one. If all three repeaters of channel oneare available, then the health or channel failure indicator may berepresented as 100% or as a “1.” As such, the various nine channels ofthe simulcast LMR system 100 may be ranked so that whenever a channelrequest is made to use such a channel, the channels may be dynamicallyallocated according to the ranked priority as provided by the preferenceindicator, which is illustrated to be a channel failure indicator.

In other embodiments, two or more preference indicators may be used todetermine how such channels are dynamically allocated. For example, achannel priority indicator may be provided to rank each such channelthat is simply a static ranking of the various channels. A radiofrequency interference indicator may be used to rank such channels, andsuch indicator may be from a periodic measurement of RF interference onthe various channels so that the ranking may be adjusted to allow forthe channel with the least amount of radio interference to be allocatedwhen requested by user. This may significantly improve overall callquality and performance of the LMR system 100. Of course, this indicatormay be weighted as desired and included as part of two or morepreference indicators for use in compiling the channel allocationpriority.

Other preference indicators may include a high reflected powerindicator, an excessive current drain indicator, a loss of backbonecommunications indicator, and a channel usage indicator. For example, ahigh reflected power indicator, similar to the radio frequencyinterference indicator, may be implemented using periodic calculationsof power being reflected on each such channel. Those channels with morereflected power are considered less desirable and thus would be rankedin a lower priority than those with less reflected power. Similarly, anexcessive current drain indicator, such as the current drain provided ata final amplifier or other amplifier of a repeater, may be measuredcontinuously or periodically, and the various repeaters andcorresponding channels may then be ranked accordingly. A channel usageindicator may include a ranking of the channels based upon the usage ofsuch channels. As such, in one embodiment, the channels that are lessfrequently used may be ranked higher to be allocated more frequently inorder to even out overall usage of the various repeaters and channels ofthe LMR system 100. Finally, and as mentioned previously, a datanetwork, not shown in FIG. 1, is provided to allow the various sites,including the first site 102, the second site 104, and the third site106 to communicate with each other. If this data network connection islost to one or more of the sites, then the loss of backbonecommunications indicator may be used to provide a dynamic channelallocation or influence the overall channel allocation priority list.

Two or more of the various preference indicators may be used todynamically allocate a channel. For example, a first preferenceindicator may include the channel failure indicator and this may beprovided a certain “weighting” in determining how the various channelsand underlining repeaters are dynamically ranked for allocation. Asecond preference indicator, such as a radio frequency interferenceindicator, may provide another “weighting” in determining how toallocate the various channels. This weighting may be provided in any ofa variety of ways, including equal weighting, unequal weighting, andsecondary weighting in the event that the first or prior preferenceindicator does not distinguish one channel from another. For example, ifthe channel failure indicator is the first preference indicator, and therepeaters for two particular channels are in service and operational,then no distinction can be made between the two channels based on thechannel failure indicator. The secondary preference indicator mayinclude a radio frequency interference indicator that indicates that onechannel is preferable or has less RF interference than the secondchannel. As such, the preferred channel may be ranked and dynamicallyallocated prior to the other, less desirable, channel.

In a preferred embodiment, a channel failure indicator (aka a channelhealth indicator) is used as a first preference indicator and it ismaintained or determined for each channel in a system. This numericalrepresentation provides a relative channel preference among the variouschannels and takes into account repeater failure status for each suchchannel. In another implementation, the radio frequency or RFinterference indicator is determined or detected by comparing a durationof consecutive RSSI samples of unassigned channels over a thresholdlevel against a configured duration (assigning the minimum value to theRFII factor). In such a case, an RF interference detection is clearedwhen the detection mechanism fails to detect for a configured durationof time. In another implementation of the radio frequency interferenceindicator, RF interference is detected or measured using a movingaverage of RF level on each channel at a time when a channel isunassigned or unallocated. In other embodiments, the channel priorityindicator is simply a static list of rankings of the various channels ofthe LMR system 100.

Although not specifically shown in FIG. 1, the dynamic channelallocation may be performed by a site controller, or other server orprocessor(s) that may be implemented at one or more of the various sitesof the LMR system 100. In a simulcast embodiment, the site controllermay be implemented at each of the three sites of the LMR system 100,with one of the site controllers designated as the active sitecontroller to perform the dynamic channel allocation as provided anddescribed herein. The remaining site controllers are provided as hotstandby or available in the event the primary or active site controllerfails. In other implementation of the LMR system 100, such as in anon-simulcast LMR system, each of the sites may include a sitecontroller or one or more processors to provide the dynamic channelallocation for each such site. In such a case, a control channel isdesignated at each location, and such control channel is used as varioustraffic channels are allocated during the operation of the LMR system100. The allocation of various channels may use the dynamic channelallocation methods and processes described and provided herein. Aspreviously mentioned, the various preference indicators and rankings maybe performed periodically or may be adjusted upon a change in one ormore of the preference indicators.

FIG. 2 is an overview diagram that illustrates an exemplary site 102,such as site 102 of FIG. 1, of an LMR system that is in communicationwith a mobile radio unit 170. The site 102 includes an antenna 150,shown communicating with the mobile radio unit 170, as well as theplurality of repeaters 110, which, as in FIG. 1, includes ninerepeaters, in this particular embodiment. The site 102 also includes asite controller 160, which may be implemented as one or more servers orcomputers and will include one or more processors 162, memory and/orstorage 164, and a dynamic channel allocation system 166, which is shownin FIG. 2 at the dashed box. The dynamic channel allocation system 166may be implemented in software or code using a site controller 160 orusing an external system dedicated for such application, or using adistributed processing system at different locations. In oneimplementation, the dynamic channel allocation system 166 is implementedusing instructions carried out by the one or more processors 162 of thesite controller 160.

Just as in FIG. 1, the backbone data network connecting the site 102 toother sites of an LMR system is not specifically shown. In a simulcastLMR system, an active site controller 160 may be provided at one or moreof the sites of the LMR system, or at a separate location that is incommunication with the one or more sites of the LMR system. In anon-simulcast system, each site of the LMR system will generally haveits own site controller, and such site controller may be configured orimplemented to carry out the dynamic channel allocation as describedherein. In other embodiments, a dedicated computer or system is providedto provide such dynamic channel allocation functionality.

FIG. 3 is a flow chart that illustrates an exemplary method 300 fordynamic channel allocation in an LMR system. The method 300 includesusing at least one preference indicator, such as the channel failureindicator (which also may be referred to as a health preferenceindicator) to allocate a control channel and/or one or more trafficchannels in an LMR system.

The method 300 for dynamic channel allocation begins at 302 where one ormore preference indicators for a plurality of channels are determined.For example, in a simulcast system where each of the various channelsare made up of repeaters located at each of the plurality of sites ofthe LMR system, various preference indicators may be determined ormeasured to assist with determining how to dynamically allocate suchchannels when a request is made to allocate either a control channel ora traffic channel. Of course, a control channel is generally initiallyallocated at startup and is used to assist with allocating trafficchannels thereafter. It should be understood, that the allocation ofboth the control channel and the various traffic channels may beallocated using the dynamic channel allocation as provided and describedherein. In other implementations, either the control channel isallocated using dynamic channel allocation or the traffic channels areallocated using the dynamic channel allocation, as may be provided in aparticular implementation or embodiment.

Proceeding next to step 304, a priority ranking is determined based on aone or more preference indicators. In the case of only one preferenceindicator being used, and in a preferred embodiment, a channel failureindicator is used to rank the various channels. This helps ensure thatfully functioning channels that include all or most repeaters areallocated first. This provides better overall performance to users ofsuch an LMR system. Depending on a particular embodiment, the priorityranking of the method 300 as provided in 304 may be implemented using aweighted average of two or more preference indicators, as previouslydiscussed, or may use succeeding preference indicators until a preferredchannel is identified.

Proceeding next to 306, a first channel allocation request is received,such as when the LMR system is first operational or at a later time, anda control channel is allocated at 308 as indicated in the method 300.The allocation of the control channel is provided using the dynamicchannel allocation based on the one or more preference indicatorspreviously described. Once the control channel is allocated, the method300 proceeds next to step 310. At 310, a second channel allocationrequest is received, and the current priority ranking for the variouschannels is accessed at step 312, where the highest priority rankedchannel is then allocated as a traffic channel. Successive trafficchannel allocations may then be allocated by proceeding back to step 310where a third channel allocation request may be received and the nextpriority ranking is used to allocate such a request. Of course, thepriority ranking in the various one or more preference indicators may beperiodically updated, continuously updated, and/or updated as conditionsand/or characteristics of the LMR system change. For example, a radiointerference indicator, a high reflected power indicator, or anexcessive current drain indicator may all vary over time depending onthe operational characteristics and conditions of the various sites,repeaters and channels of the LMR system.

The channel failure indicator corresponds to the current operationalstate of the plurality of repeaters associated with a channel in asimulcast LMR system, and it may be calculated based upon a percentageor value equal to or less than one. In one implementation, this may beused as the initial determination for ranking and allocating the variouschannels, while a channel priority indicator, which is simply a staticranking of each of the plurality of channels, may be used as a second orthird preference indicator. Of course, a variety of other preferenceindicators may be used such as a radio frequency interference indicator,a high reflected power indicator, an excessive current drain indicator,which measures the current drain and an amplifier of a repeater, a lossof backbone communications indicator, and a channel usage indicator. Anyof a number of these indicators may be used so that a dynamic channelallocation may be provided. Ultimately, a priority ranking is providedso that when a channel request is received by the LMR system, apreferred or desired channel may be expeditiously allocated.

FIG. 4 is a flowchart that illustrates another exemplary method 400 fordynamic channel allocation in an LMR system. The method 400 begins atblock 402 where a first preference indicator is determined for each ofthe plurality of channels. In this embodiment, the first preferenceindicator includes a channel failure indicator, which may be thought ofas a health indicator of the various channels. As previously discussed,the channel failure indicator is based upon the operational status ofthe one or more repeaters that make up each of the plurality ofchannels. Proceeding next to 404, a second preference indicator isdetermined for each of the plurality of channels. The second preferenceindicator may include one or more of the preference indicators andinclude a channel priority indicator, a radio frequency interferenceindicator, and a high reflected power indicator, which may beimplemented using testing or measurement equipment to periodically orcontinuously measure the reflected power of the various channels.

The method 400 proceeds next to 406 where a priority ranking isdetermined for use in dynamically allocating each of the plurality ofchannels. This priority ranking is determined based at least in part onthe first preference indicator, which includes the channel failureindicator. It may also be partially based on the second preferenceindicator as well.

Proceeding next to 408, in operation, an LMR system may periodicallyreceive channel allocation requests. In such a case, the method 400proceeds to 410 where a channel is dynamically allocated based upon thecurrent priority ranking of the various available channels. Aspreviously discussed and as provided above in FIG. 4, the priorityranking may be determined based on a channel failure indicator andvarious one or more secondary preference indicators.

An overview of certain implementations, examples, and embodiments of asystem and method dynamic channel priority is provided below. Whenchannel requests are made by a subscriber radio on a P25 controlchannel, a channel is selected from the pool of available trafficchannels. When the pool of available traffic channels contains channelswith different priorities, the traffic channel with the highest priorityis chosen. When there is more than one channel with the same highestpriority, the one that was least recently used is chosen, in order todistribute the allocation of channels with common priority.

In a preferred embodiment, the channel allocation priority isdynamically determined using a weighting of channel health and aconfigured static channel priority, as previously discussed inconnection with the channel failure indictor and the channel priorityindicator. A user configurable static channel priority exists for eachchannel in the system. This may range from 1-28, in one embodiment, with1 being the highest static priority. Channel health, or the channelfailure indicator, may be expressed as a percentage of the number ofsites having fully operational repeaters for that channel, rounded tothe nearest percent. (0-100).

In one example, the dynamic channel allocation priority may bedetermined as provided by the following weighting: Total Dynamic ChannelAllocation Priority=(29−StaticPriority)+(100*ChannelHealth). Theconstants 29, and 100, are chosen such that the overall Dynamic ChannelAllocation Priority may include of a 5 digit number, in this embodiment,represented as HHHSS, where HHH is Channel Health (000-100), and SS isStatic Priority (01-28). In this particular embodiment, this places moresignificance on the channel health than its static priority, even whenthere is only a single working repeater out of a potential of over 300sites.

Various failure scenarios may include the following:

Failure Scenario 1: consider the failure scenario of a nine channel,three site system, with one repeater failure, and some or all channelswith a static channel priority of 15. The eight fully operationalchannels have a Dynamic Priority of Channel Health=3/3*100=100, and anoverall weighted Total Dynamic Channel AllocationPriority=(29−15)+(100*100)=10014, while the one channel with the failedrepeater has a weighted Total Dynamic Channel AllocationPriority=(29−15)+(100*67)=6714. In this case, the eight fullyoperational channels would be assigned before considering the use of thechannel with one non-operational repeater. This results in full RFcoverage except when the system reaches maximum capacity.

Failure Scenario 2: consider the failure scenario of a nine channel,three site system, with nine repeater failures at one site, and some orall channels with a static channel priority of 15. In such a situation,the channels have a weighted Total Dynamic Channel AllocationPriority=(29−15)+(100*67)=6714. In this case, the channels may haveequal priority, resulting in full capacity, but with reduced RFcoverage. The same method can be applied to selecting a preferredcontrol channel.

In an alternative embodiment, the channel allocation priority may bedynamically determined using a combination of channel health, theabsence of RF interference, and a configured static channel priority. Asin the preferred embodiment, a user configurable static channel priorityis provided for each channel in the system. This ranges from 1-28, inthis embodiment, with 1 being the highest static priority. As in thepreferred embodiment, the Channel health, or the channel failureindicator, may be expressed as the percentage of the number of siteshaving fully operational repeaters for that channel, rounded to thenearest percent. (0-100). The RF Interference (RFI) Indicator (RFII) isan assessment of the quality of the channel in consideration of detectedRF interference, ranging from 0-100, where 100 indicates no RFIdetected, and 0 indicates the worst level of RFI detected. This may bereferred to as the RF interference indicator. In this embodiment, thereare only two levels of RFI, 0 and 100. RFII is initially assumed to beat 100, i.e., no interference. The receive signal strength is sampledonce per second, in this example. While a channel is not assigned fortraffic, the number of consecutive samples at or above a configuredthreshold is used to indicate the presence of RF interference on thechannel. After reaching this threshold, the RFII is set to 0 and staysat 0 until the detection of RFI, using this method, results in no RFIdetected for a configured duration of time, at which time the RFII isset to 100.

In this alternative embodiment, the weighted Total Dynamic ChannelAllocationPriority=(29−StaticPriority)+(100*RFII)+(100000*ChannelHealth). Theconstants 29, 100, and 100000, are chosen such that the overall TotalDynamic Channel Allocation Priority will be an eight digit number inthis embodiment, represented as HHHIIISS, where where HHH is ChannelHealth (000-100), III is Interference Indicator (000-100), and SS isStatic Priority (01-28). In this alternative embodiment, this placesmost significance on the channel health, followed by RF Interference,and finally static priority.

In the foregoing description of certain embodiments, specificterminology has been resorted to for the sake of clarity. Thedisclosure, however, is not intended to be limited to the specific termsso selected, and it is to be understood that each specific term includesother technical equivalents which operate in a similar manner toaccomplish a similar technical purpose. Terms such as “left” and right”,“front” and “rear”, “above” and “below”, “first” and “second”, and thelike are used as words of convenience to provide reference points ordistinction points and are not to be construed as limiting terms or astime dependent terms.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

In addition, the foregoing describes only some embodiments of theinvention(s), and alterations, modifications, additions and/or changescan be made thereto without departing from the scope and spirit of thedisclosed embodiments, the embodiments being illustrative and notrestrictive.

Furthermore, invention(s) have described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention(s). Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of any given assembly may constitute an additional embodiment.

The invention claimed is:
 1. A method for dynamic channel allocation ina land mobile radio communication system, the method comprising:determining one or more preference indicators for one or more channelfor use in allocating at least one of the one or more channels;determining a priority ranking for use in allocating at least one of theone or more channels based at least in part on the one or morepreference indicators; receiving a first channel allocation request toallocate at least one channel of the one or more channel; allocating afirst channel of the one or more channel in response to the firstchannel allocation request by selecting the first channel of the one ormore of channels based at least in part on a then highest ranked channelof the priority ranking used in allocating the one or more channel, andwherein the one or more preference indicators includes a channel failureindicator for each of the one or more channel that corresponds to acurrent operational state of a plurality of repeaters associated witheach of the one or more channel, and a channel priority indicator thatincludes a static ranking of each of the one or more channel.
 2. Themethod of dynamic channel allocation according to claim 1, furthercomprising: updating the priority ranking for use in allocating at leastone of the one or more channels based at least in part on changes to theone or more preference indicators.
 3. The method of dynamic channelallocation according to claim 1, wherein the channel failure indicatoris determined based on a percentage of operational repeaters associatedwith the at least one of the one or more channel as compared to a totalnumber of repeaters associated with the at least one of the one or morechannel.
 4. The method of dynamic channel allocation according to claim1, wherein the one or more preference indicators further include atleast one from a group that comprises a radio frequency interferenceindicator, a high reflected power indicator, an excessive current drainindicator, a loss of backbone communications indicator, and a channelusage indicator.
 5. The method of dynamic channel allocation accordingto claim 1, wherein the land mobile radio communication system is asimulcast land mobile radio communication system.
 6. The method ofdynamic channel allocation according to claim 1, wherein the land mobileradio communication system includes a plurality of sites positioned atseparate locations and in data communication with one another using adata communications network.
 7. A method for dynamic channel allocationin a land mobile radio communication system, the method comprising:determining a first preference indicator for a channel for use inallocating the channel, wherein the channel is associated with one ormore repeaters of the land mobile radio communication system, andwherein the first preference indicator includes a channel failureindicator for the channel that corresponds to a current operationalstate of the one or more repeaters associated with the channel;determining a priority ranking for use in allocating the channel basedat least in part on the first preference indicator that includes thechannel failure indicator for the channel; determining a secondpreference indicator for the channel for use in allocating the channelassociated with the one or more repeaters, wherein the second preferenceindicator is associated with the channel and includes one or more fromthe group consisting of a channel priority indicator, a radio frequencyinterference indicator, and a high reflected power indicator, whereindetermining the priority ranking for use in allocating the channel isbased at least in part on both the first preference indicator and thesecond preference indicator; receiving a channel allocation request; andallocating the channel in response to the channel allocation request byselecting the channel based at least partially on the priority rankingfor allocating the channel being greater than a second priority rankingof a second channel.
 8. The method of dynamic channel allocationaccording to claim 7, wherein the second preference indicator for use inallocating the channel is the radio frequency interference indicatorthat corresponds to radio frequency interference levels for thechannels.
 9. The method of dynamic channel allocation according to claim7, wherein the second preference indicator for use in allocating thechannel is the high reflected power indicator that corresponds toreflected power levels related to the channel.
 10. The method of dynamicchannel allocation according to claim 7, wherein the allocated channelis a control channel.
 11. A land mobile radio communication system withdynamic channel allocation to provide mobile communications between atleast two of a plurality of radio subscriber units, the land mobileradio communication system comprising: one or more processors configuredto provide dynamic channel allocation, the one or more processorsconfigured to: determine one or more preference indicators for at leastone of a two or more channels for use in allocating the at least one ofthe two or more channels; determine a priority ranking for use inallocating at least one of the two or more channels based at least inpart on the one or more preference indicators; receive a first channelallocation request to allocate at least one channel of the two or morechannels as a control channel; allocate a first channel of the two ormore channels as the control channel in response to the first channelallocation request by selecting the first channel of the two or morechannels based on the highest ranked channel of the priority ranking foruse in allocating at least one of the two or more channels; receive asecond channel allocation request to allocate at least a second channelof the two or more channels as a traffic channel while the first channelof the two or more channels is allocated as the control channel; andallocate a second channel of the two or more channels as the trafficchannel in response to the second channel allocation request byselecting the second channel of the two or more channels based on thethen highest ranked channel of the priority ranking for use inallocating at least one of the two or more channels.
 12. The land mobileradio communication system of claim 11, wherein the land mobile radiocommunication system is a P25 trunking system.
 13. The land mobile radiocommunication system of claim 11, wherein the one or more processors arefurther configured to: update the priority ranking for use in allocatingat least one of the one or more channels based at least in part onchanges to the one or more preference indicators.
 14. The land mobileradio communication system of claim 11, wherein the one or morepreference indicators includes at least one from a group that comprisesa channel failure indicator, a channel priority indicator, a radiofrequency interference indicator, and a high reflected power indicator.15. The land mobile radio communication system of claim 11, wherein theone or more preference indicators includes a channel failure indicatorfor at least one of the one or more channel that corresponds to thecurrent operational state of the plurality of repeaters associated withthe at least one channel, and a channel priority indicator that includesa static ranking of the one or more channels.
 16. The land mobile radiocommunication system of claim 11, wherein the one or more preferenceindicators include a channel priority indicator that includes a staticranking of the one or more channels.
 17. The land mobile radiocommunication system of claim 11, wherein the land mobile radiocommunication system is a simulcast land mobile radio communicationsystem.